Phases of the menstruation cycle

Ok, so the menstruation cycle is the time between the first day of one period and the first day of your next period. The amount of time it takes for this to happen is about a month (the average menstrual cycle lasts 28 days). So what’s the ‘cycle’ bit all about? Well, one complete cycle is made up of these phases below.

Phase 1: Menstruation (having your period)

What's happening? Your body is getting rid of tissue it doesn’t need.

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When you menstruate, the lining of the uterus (the endometrium) breaks up and passes slowly from the uterus through the vagina to the outside of your body. This menstrual ’flow’ drips out slowly. It can look like a lot of blood (it’s only about 35 ml blood…some women lose more), but it’s actually a mixture of blood, mucus, and body cells amounting to a total of about 6–9 tablespoons (or about 80–85 ml) of menstrual fluid on average for each period. The flow might be red or quite dark, and might include some clumps or clots.

Phase 2: Pre-ovulation phase (right after your period ends)

What's happening? Your body is preparing an egg for pregnancy.

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About the time your flow stops, your ovaries start to prepare another egg, or ovum, for release into one of the fallopian tubes (usually, the ovaries take turns releasing eggs—the left ovary one month, the right ovary the next month). At the same time, a hormone called oestrogen tells your uterus to build up the endometrium.

Phase 3: Ovulation

What's happening? A lot during this phase, but basically the egg is released from the ovary into the fallopian tubes, and your body is preparing the uterus to receive a fertilised egg (if there is one).

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As Phase 2 ends, your brain sends a new hormonal signal to your ovaries, telling one ovary to release the mature egg (ovum). This step is called ovulation.

• First, the egg moves through the fallopian tube toward the uterus.

• At the same time, the endometrium is growing even thicker because of the hormone progesterone.

This happens so the body is ready in case the egg is fertilised. If the egg isn’t fertilised, your body knows that it doesn’t need its ‘nest’ anymore.

Although the menstruation cycle can vary in length, the number of days between ovulation and the menstrual period is fairly consistent. Ovulation usually occurs 14 days before the start of your next period.

Phase 4: The Premenstrual (luteal) phase

What's happening?

If a woman hasn’t become pregnant, the uterus gets ready to release the unneeded tissue that was prepared for the egg.

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Levels of two hormones involved in the development of the uterine lining, oestrogen and progesterone, begin to drop. The stimulation for the endometrium is lost. This causes the shedding of the lining to begin, and a new menstrual cycle starts.